levelImage

Adjusts the levels of an image by scaling the colors falling
between specified white and black points to the full
available quantum range. The parameters provided represent
the black, mid, and white points. The black point specifies
the darkest color in the image. Colors darker than the black
point are set to zero. Mid point specifies a gamma
correction to apply to the image. White point specifies the
lightest color in the image. Colors brighter than the white
point are set to the maximum quantum value.

Adjusts the levels of an image by scaling the colors falling
between specified white and black points to the full
available quantum range. The parameters provided represent
the black, mid, and white points. The black point specifies
the darkest color in the image. Colors darker than the black
point are set to zero. Mid point specifies a gamma
correction to apply to the image. White point specifies the
lightest color in the image. Colors brighter than the white
point are set to the maximum quantum value.